1. Field of the Invention
The present invention relates to a refrigerator defrost controlling method, and more particularly, to a refrigerator defrost controlling method for adjusting a defrost cycle and a defrost restoration temperature by detecting a latent heat period obtained by a change in temperatures of a defrost sensor.
2. Description of the Related Art
Generally, a refrigerator repeatedly executes a cooling cycle comprised of compression, condensation, expansion and evaporation of a refrigerant, so that a high-temperature refrigerant gas discharged from a compressor is formed on an evaporator to then generate frost. To overcome such a problem, conventionally, the frost formed on the evaporator is removed by detecting the number of rotations of a fan motor in the refrigerator and performing a defrost operation according to the detected number of rotations.
FIG. 1 is a circuit diagram of a conventional refrigerator defrosting apparatus, in which a first defrost sensing circuit 12 detects the temperature of an evaporator (not shown) to sense the frost formed on the evaporator using a first defrost sensor 11. A controller 15 accumulates defrost entering times from the temperature detected by the first defrost sensing circuit 12 to generate a defrost control signal, and generates an alarm control signal according to a temperature detected by a second defrost sensing circuit 14. A heater drive and display portion 17 drives first and second light emitting diodes LED1 and LED2 by means of a driver 16 according to the defrost control signal generated from the controller 15, and controls a relay switch RY.sub.-- SW to drive first and second defrost heaters H1 and H2 via a relay RY. The second defrost sensing circuit 14 detects the temperature of the evaporator using a second defrost sensor 13 to sense the frost which is not removed during the defrost operation. An alarming portion 18 alarms a defrost state using a buzzer BZ according to the alarm control signal generated from the controller 15.
FIG. 2 is a flowchart of a procedure for illustrating a defrost controlling method of the refrigerator defrosting apparatus shown in FIG. 1, which is performed by the controller 15. In step S211, a cooling operation is performed by driving a compressor (not shown). In step S212, the operating time of the compressor in the step S211 is accumulated. In step S213, it is determined whether the operating time accumulated in the step S212 reaches a predetermined defrost entering time, i.e., a first reference value. In step S214, if the compressor operating time is a first reference value, the driving of the compressor is stopped. If not, the procedure returns to step S211. After performing step S214, the controller 15 outputs the defrost control signal to remove the frost formed on the evaporator by the defrost heater in step S215. In step S216, the number of defrost operations performed in step S215 is counted. In step S217, it is determined whether the counted number of defrost operations reaches a predetermined number, i.e., a second reference value. In step S218, it is determined whether the detected temperature of the first defrost sensor 11 is a defrost-off temperature in case that the counted number of defrost operations is not the second reference value in step S217, and steps S216 through S218 are repeatedly performed until the detected temperature of the first defrost sensor 11 reaches the defrost-off temperature. If the detected temperature of the first defrost sensor 11 reaches the defrost-off temperature, in step S219, it is determined whether the detected temperature of the first defrost sensor 11 and that of the second defrost sensor 13 equals to each other and steps S216 through S219 are repeatedly performed until the temperatures become equal to each other. In step S220, it is determined whether the detected temperature of the second defrost sensor 13 is a defrost-off temperature in case that the counted number of defrost operations is the second reference value in step 217. Step S220 is repeatedly performed until the temperature of the second defrost sensor 13 reaches the defrost-off temperature. If the temperature of the second defrost sensor 13 reaches the defrost-off temperature, in step S221, the number of accumulated defrost operations is cleared, and the defrost operation is suspended by stopping the driving of the defrost heater in step S222. Then, the routine goes back to step S211.
In the conventional refrigerator defrosting apparatus having the aforementioned configuration, the defrost operation for removing the frost formed on an evaporator is performed by the number of times set according to the temperature detected by a first defrost sensor. If the temperature of a second defrost sensor is not a defrost-off temperature even after the predetermined number of defrost operations are performed, the defrost operation is continuously performed while alarming that the defrost operation is being performed, thereby removing the frost which is not removed from the evaporator.
However, according to the above-described conventional refrigerator defrost controlling method, irrespective of the amount of the frost formed on the evaporator, the defrost operation is performed according to accumulation of the operating time of a compressor. Thus, in the case when the frost is excessively formed due to wet load of a refrigerator, the defrost operation is performed inefficiently. As a result, the cooling efficiency of the refrigerator is lowered, which increases power consumption.